Yakazu: rules and how to play

Goal of the game

Fill the white cells so that every horizontal and vertical run contains exactly the numbers required by its length. Black cells divide the grid into separate runs.

Rules

• A run is an uninterrupted straight line of white cells between black cells or the edge.
• Each run of N cells, with N at least 2, contains 1 through N once each, in any order. Keep given digits.
• At a crossing, both runs constrain the same cell. A length-one run imposes no separate 1 requirement; use the crossing run. In this variant, a cell isolated in both directions takes 1.
• There is no whole-row or whole-column uniqueness rule across black separators.

A small example, step by step

1. Take a horizontal run of three cells containing 1, _, _.
2. Suppose its middle cell also belongs to a vertical run of two cells. That cell can only be 1 or 2.
3. The horizontal 1 excludes another 1, so the middle cell is 2. The last cell is then 3.
4. Recheck the crossing vertical runs before continuing: each placement constrains both directions.

Beginner deductions

• Begin with nearly complete runs. Subtract the placed numbers from 1–N.
• Intersect the possibilities from both crossing runs. A run of two limits a crossing cell to 1 or 2, even inside a longer run.
• If a missing number has only one possible cell in a run, place it there. Revisit crossings after every placement.

Common mistakes

• Do not force 1 merely because a cell has no white neighbour in one direction.
• Do not carry a no-repeat restriction across a black cell.
• Count each run separately; the overall grid width is not its digit limit.

Controls and availability

Select a white cell, then enter a number using the keypad or keyboard. Draft mode records candidates; Undo reverses an edit and Clear all resets the board. Pause stops active play; the ? button opens the quick rules. Progress is saved in this browser. Human difficulty calibration remains pending.

Difficulty

The intended difficulty contract is Easy, Medium and Hard solved entirely by logical deductions, with zero hypotheses. Hard may require longer chains or more demanding techniques. Expert may allow an explicit hypothesis, following its consequences and rejecting it if it contradicts a rule. A unique solution alone does not prove a logical solving path. Unclassified means not yet graded, not automatically Expert. Human calibration remains pending; these are requirements, not a claim that all bands are available.

FAQ

Do I need Premium to read this guide?

Premium unlocks the catalogue. A verified member can also create a grid for 10 DIG and always play their own creations.

Does a difficulty label guarantee a calibrated game?

Not during this preview. Human review is pending. The intended distinction is deductions only for Easy/Medium/Hard; hypotheses may be used in Expert.

What if I cannot find a move?

Recheck the rules and the last certain steps, then revisit the deductions above. Keep possibilities separate from confirmed answers; being stuck is not proof that guessing is necessary.